Recently, a keyless lock of the type requiring the use of no key has been popularized as a door lock to be used for individual dwelling houses, companies, shops, hospitals and the like.
As a keyless lock of the type mentioned above, there are a so-called mechanical lock in which the locking and unlocking procedure is made by a structural means and an electric or electronic lock in which the locking and unlocking procedure is made by an electrical means.
Of these two types of keyless locks, the mechanical lock, when compared with the electronic or electric lock, has such advantages that there is no worry about power failure or battery exhaustion because no wiring work is required, the user of such a lock is free from electrical trouble such as malfunction, and in addition, the mechanical strength is large.
The mechanical lock, in general, includes a plurality of control buttons. Memory information corresponding to the control buttons is stored in association with a cam or link mechanism or a gear train, the memory information of the respective control buttons is combined by the same number as the number of the control buttons, and a password number consisting of the number of digits of the control buttons is set or inputted. At the time of unlocking, the control buttons corresponding to the password number are operated so that the lock can be unlocked.
For example, in the invention disclosed in Japanese Patent Publication No. S62-54951 the present applicant previously filed, the respective control buttons are inserted in the slits formed in a case frame in their erected or inverted states, and the numbers of the respective control buttons are set to 1 or 0, i.e., two modes of either “set” or “unset”. Then, it is selectively decided whether the number setting for the respective control buttons is necessary or not so that the password number can be set or inputted by a combination of the corresponding numbers. At the time of unlocking, the control buttons for which the number setting has been made are depressed to engage the slits formed in those buttons with the keyplate. On the other hand, the control buttons for which the number setting has not been made are not depressed to maintain the engagement relation between the slits and the keyplate. Owing to this arrangement, the cam pin can be turned to allow the handle to turn, so that the lock can be unlocked.
However, in this conventional device, since only two modes, i.e., number setting and number unsetting, can be obtained for each control button and the setting amount of information for each control button is limited, the number of the password number depends on the number of the control buttons and thus, a sufficient setting amount of information is unobtainable. Since the range of selection thereof is limited, a large enough safety performance is unobtainable.
In order to solve those problems, if the number of the control buttons should be increased, the number of the component parts would be increased to that extent. Thus, the construction and the locking and unlocking procedure becomes complicated, and the case frame and the packing plate become large in size, thus resulting in large size and heavy weight of the entire button-operated lock. Moreover, the outer appearance of the door is degraded.
Those problems are also common in U.S. Pat. No. 3,115,765.
That is, the lock disclosed in the above U.S. patent includes a generally elongate box-like casing. This casing is retractably provided at a face plate thereof with a plurality of key systems which are linked to the control buttons. A plurality of shafts are turnably suspended in the longitudinal direction of the casing. The respective gears are engageably arranged in such a manner as to face with the key system positions of those shafts. The gears are intermittently turned through the pressing operation of those key systems. A control shaft, which is linked to a door handle is disposed at one end of the casing. A slide plate is provided in such a manner as to be engageable with a cam disposed at the control shaft. A plurality of engagement elements disposed at the slide plate are engageable with and disengageable from the respective gears which are fixed to the above-mentioned shaft. The memory system by the key system can be stored in the gear train or reset.
However, the lock taught by the above U.S. patent has the following problems. Since each control button can set only a single memory information, a combination of memory information achievable through each control button is limited, and selection of password numbers and safety performance are limited. Moreover, since the number setting of the control buttons is linked to the number setting of the adjacent control buttons and the password number is stored in order of the setting input, the number setting lacks in versatility and the smooth execution of the locking and unlocking procedure is jeopardized. Moreover, since the turning force of the door handle acts on the slide plate, it can easily be perceived whether or not memory setting has been made through the respective control buttons. This, together with the above-mentioned disadvantage in limitation of the memory capacity, tends to create such a fear that repeated evil attempt should be made on the control buttons, the lock could be unlocked comparatively easily.
On the other hand, a long time use of a same password number leads gives a chance to a third party to perceive and decode the number. This is not desirable in view of protection of the password number. Therefore, it is desirable that the password number is altered frequently. However, since the alternation mechanism and operation thereof requires a time-consuming troublesome work in view of its structure, the simplification and easiness are demanded.
For example, the lock proposed by the present applicant in Japanese Patent Publication No. S62-54951 is designed such that at the time for altering the password number, a case frame and a packing plate, which are arranged at the inside and the outside of the door, is removed therefrom, the corresponding control buttons are pulled out in their exposed states, and inserted into a slit in their erected or inverted states and then reassembled.
However, this method has such problems that since the case frame and the backing plate are required to be detached from the door and the buttons are required to be detached or replaced, complicated and time-consuming work is required.
In the lock of the above-mentioned U.S. Pat. No. 3,115,765, at the time for altering the password, the control buttons are operated to set or input the current password number and thereafter, the slide plate is moved to release the engagement between the engagement element and the groove. After the current password number is canceled, the control buttons are operated to set or input a new password number.
This method, when compared with the above-mentioned method, has such advantages that the troublesome work for removing the related parts from the door is no more required and thus, this operation can be made in a simple and convenient manner. However, it has such a problem that since the password number can be altered from the outside of the door, the third party can make a falsification relatively easily. Therefore, uneasiness in relation to protection and security occurs.
It is, therefore, a main object of the present invention, to provide a button-operated lock which is capable of solving the above-mentioned problems and in which the amount of information to be set to the control buttons is increased, a large setting amount of information and its wide selection can be obtained, and safety performance can be enhanced.
Another object of the present invention is to provide a button-operated lock, in which the structure can be simplified and made compact and light-weight, and the manufacturing cost can be reduced.
A further object of the present invention is to provide a button-operated lock, in which the setting or inputting of information to the control buttons, as well as an altering operation thereof, can be made correctly, safely, easily and rationally.
A still further object of the present invention is to provided a button-operated lock, in which decoding or perceiving of information, which would otherwise be made by the third party relatively easily, is prohibited so that the third party is prevented from making a falsification and/or conversion of such information.
A yet further object of the present invention is to provide a button-operated lock, in which a criminal unlocking procedure, which would otherwise be made by the third party comparatively easily through a control hole formed in a case, can be prevented from occurring.